OFFSET
1,2
COMMENTS
If gcd(m,n) = 1 then a(m*n) = (a(m) * a(n)) mod 9. - Robert Israel, Sep 14 2014
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
FORMULA
MAPLE
seq(numtheory:-sigma(n) mod 9, n=1..1000); # Robert Israel, Sep 14 2014
MATHEMATICA
Mod[DivisorSigma[1, Range[100]], 9] (* Wesley Ivan Hurt, Apr 25 2023 *)
PROG
(PARI) a(n)=sigma(n)%9
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Shyam Sunder Gupta, May 05 2005
EXTENSIONS
Name corrected and keyword base removed by Michel Marcus, Sep 14 2014
STATUS
approved